A Long-Term Evolution Advanced (LTE-A) system has evolved from the Long-Term Evolution (LTE) system to meet the requirements of International Mobile Telecommunication-Advanced (IMT-A). While the LTE system may support a bandwidth of a maximum of 20 MHz, the LTE-A system may support broadband services based on a bandwidth of a maximum of 100 MHz, using the Carrier Aggregation (CA) technology.
Uplink/Downlink (UL/DL) resource allocation information, transmission format information, UL power control commands and the like may be contained in Downlink Control Information (DCI), and transmitted from a transmitter (for example, base station) to a receiver (for example, terminal) over a Physical Downlink Control Channel (PDCCH) in a control region. A carrier signal on which data is carried may be different from a carrier signal on which DCI is carried, and this is referred to as ‘cross-carrier scheduling’.
For high-speed data transmission, carrier signals of a wide bandwidth in a high-frequency region may be aggregated. Generally, a receiver consumes more power for a carrier signal in the high-frequency region than a carrier signal in a low-frequency region, in order to check the carrier signal in the high-frequency region. Therefore, in terms of power consumption of the receiver, it is efficient that scheduling information for data, which is carried on the carrier signal in the high-frequency region, is delivered over a PDCCH of another carrier signal in the low-frequency region, using cross-carrier scheduling. The term ‘high-frequency region’ as used herein may refer to an ultrahigh frequency band of, for example, 5 Giga-hertz (GHz) to 60 GHz.
In order to efficiently support carrier signals of a broadband in the high-frequency region, a new transmission mode needs to be added, or more precise UL power control needs to be used. However, due to the limited number of bits of the DCI format defined in the LTE-A standard, in order to add new information fields in DCI or increase the number of bits of the existing fields, other fields need to be deleted or the number of bits used in the other fields needs to be reduced. For example, if the number of bits allocated for data transmission is reduced, granularity of resource allocation for the data to be carried on carrier signals of a broadband in the high-frequency region may be reduced undesirably. Therefore, there is a need for a method of efficiently transmitting and receiving a large amount of control information using cross-carrier scheduling in a wireless communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.